1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to an exposing device which can form a micron pattern even with an exposing device having a low resolving power by changing a mask pattern, methods for forming a pattern, a channel, and a hole respectively, and a liquid crystal display device therewith and a method for fabricating the same.
2. Discussion of the Related Art
A related art method for forming a pattern will be described with reference to the attached drawings.
FIG. 1 schematically illustrates a method for forming a pattern by using a related art exposing device.
Referring to FIG. 1, the method for forming a pattern by using a related art exposing device has the following steps.
First, a thin film 4 to be patterned is deposited on a substrate 3, and a photoresist film 5 is coated on the thin film 4.
Then, an exposing device 1 which can emit a light with a wave length longer than 300 nm and a mask 2 which can project an image of a predetermined pattern to the photoresist film 5 upon reception of the light from the exposing device 1 are arranged over the photoresist film 5.
The mask 2 has a light transmission portion 2a and a light shielding portion 2b defined therein, wherein the light transmission portion 2a defines a portion that exposes the photoresist film 5 to the light, and the light shielding portion 2b defines a portion that shields the light. For example, if the photoresist film 5 has a positive light sensitivity, the portion of the photoresist film 5 corresponding to the transmission portion 2a is a portion to be removed after exposure and development, and the portion 5a of the photoresist film 5 corresponding to the light shielding portion 2b is a portion to be remained after the exposure and development. If the photoresist film has a negative light sensitivity, the photoresist film will be oppositely patterned.
FIG. 2 illustrates a plan view of an exemplary related art mask.
Referring to FIG. 2, the related art mask has line shapes of the shielding portions 2b, and the other region defined as the transmission portion 2a. For example, the mask shown in FIG. 2 can form gate lines, data lines, or pixel electrodes or common electrodes in correspondence to the line shaped light shielding portions 2b in the case of a liquid crystal display device. In this case, a width A of the light shielding portion 2b or a gap A′ between the light shielding portions 2b which is to be formed at the mask 2 can be fixed by a resolving power of the exposing device 1, wherein the stronger the resolving power of the exposing device 1, a pattern having the finer width A or gap A′ of the light shielding portions 2b and the light transmission portions 2a can be formed. That is, even if the width A and the gap A′ of the light shielding portions 2b and the light transmission portions 2a can be made thin in the mask 2, it is difficult to form the pattern as desired under the mask 2 at the time of exposure if the exposing device 1 has a low resolving power. In this instance, if the photoresist film 5 has positive sensitivity, the portion of the substrate corresponding to the light shielding portion 2b will be the portion that remains of the photoresist film 5 after the exposure and development, and the portion of the substrate corresponding to the light transmission portion 2b will be the portion removed from the photoresist film 5 after the exposure and development.
FIGS. 3A and 3B illustrate photographs of examples in which patterns are formed with a related art mask and a regular resolving power of the exposing device and a resolving power higher than the exposing device, respectively.
Referring to FIG. 3A, when a pattern is formed on the photoresist film with a mask shown in FIG. 2 and a regular resolving power of the exposing device (a pattern greater than 4 μm can be formed), widths of portions that remain in, and are removed from the photoresist film after the exposure and development are fixed in proportion to a ratio of the light shielding portion 2b to the transmission portion 2a of the mask 2, and formed uniformly without defect.
However, referring to FIG. 3B, when a micron pattern of a size below 4μ is formed with a resolving power higher than the exposing device, because the resolving power of a wave length of a light from the exposing device is greater than the widths of the light transmission portion 2a or the light shielding portion 2b of the mask 2, since regular exposure on the photoresist film by the light passed through the transmission portion 2a of the mask 2 fails, defects, such as line shorts, are taken place on the portions of the photoresist film corresponding to the light shielding portions 2b of the mask after the exposure and the development.
That is, the exposing device generally used in fabrication of the liquid crystal display device has about 300 nm of wavelength emitted from the exposing device, enabling to form up to approx. 4 μm pattern line width. As far as the exposing device 1 is not changed to another equipment that has a resolving power stronger than the exposing device 1, it is difficult to form a pattern having a line width thinner than the 4 μm pattern line width, and if tries, defects, such as pattern disconnection, can take place. Therefore, improvement on this is in need.